nemo-view.c: Partially revert b4d0318

This causes a segfault when a python extension keeps a reference to
the NemoWindow given in provider.get_file_items() to use in a callback
and the window is closed.

ref: #2686

This is not a fix, just a workaround for now to prevent a crash.

src/nemo-view.c

@@ -5884,8 +5884,6 @@ add_extension_menu_items (NemoView *view,
     			g_free (subdir);
     		}
         }
-
-        g_clear_object (&menu);
 	}
 }